Melanin is a natural pigment, widely spread in the animal and vegetal kingdoms, its color varying from a deep black to a reddish brown, with many intermediate tints. Said melanin gathers in the cells at the areas in the body that are exposed to ultraviolet radiation, and forms solar screens or filters for the protection of the anatomic structures underneath.
Melanin is present in the shape of micropellets and is a product of the metabolic degrading of phenilanin, tyrosine, dehydroxiphenilanin, 5,6-quinine and 5,6-dihyroxindole-2-carboxilic acid (cumelanine).
The melanin gathered in the melanocytes of the skin, being especially found on fish, forms stains or dark surfaces more or less extended in areas which may also be part of mimetic systems. This combination of different functions of melanin (solar protection - mimetism) occurs in the sea fauna in the water near the surface, such as crustaceans (spiny lobster, prawns, crayfish).
This class of invertebrates have a slight shadowy shade, due to the melanin micropellets distributed in the teguments and shell. Out of their habitat, they acquire a dark tint that stresses as they remain in the environmental air. This process, named melanization, or melanogenesis, is due to oxidation that can be enzymatic due to condensation and polymerization of aminoacid and protein groups, or else non-enzymatic due to the formation of metallic chelates with copper and iron, of the forerunners of melanin, present in the tissues, with which the content of melanin in the same increases, thus stressing the darkening.
In conventional practice, this oxidation and darkening process is controlled, up to a certain extent, by the storage of the products at low temperatures, in cold storage chambers or, given the case, maintaining the collected products in alternate layers or in bulk with ice. This method only slows down or delays the melanization process, which is undesirable, since the darkening is a clear sign for the consumers that a preserved product is deficient and/or has been stored for a long time.
It has been proved that it is now possible to extend the preservation of sea products, subject to melanization or darkening of the body out of their habitat, especially crustaceans such as shrimp, spiny lobsters, crayfish, kril, crabs, etc. This is possible by applying a composition in which a microbicidal system and a reducing agent fuse, both being specific, and also compatible from the alimentary point of view.